How severe is CVE-2025-6543?

CVE-2025-6543 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2025-6543?

Affected package information for CVE-2025-6543 is not yet fully mapped. Check the official advisory links for details.

How do I fix CVE-2025-6543?

No fixed version has been published for CVE-2025-6543 yet. Monitor the advisory for updates, apply mitigations recommended by the vendor, and use O3 Security to track when a fix becomes available in your stack.

Is CVE-2025-6543 actively exploited in the wild?

Yes. There are 2 known exploit references for CVE-2025-6543, including . All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2025-6543?

CVE-2025-6543 has an EPSS (Exploit Prediction Scoring System) score of 1.1%, placing it in the 78th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

Is CVE-2025-6543 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2025-6543 (Citrix NetScaler ADC and Gateway Buffer Overflow Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2025-06-30. CISA required all US federal civilian agencies to remediate this vulnerability by 2025-07-21. The required action was: Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2025-6543?

CVE-2025-6543 is classified as Buffer Overflow (CWE-119). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2025-6543?

CVE-2025-6543 affects citrix netscaler application delivery controller; citrix netscaler gateway. Check the affected-products list on this page against your deployed version to confirm exposure.

When was CVE-2025-6543 published, and has it been updated?

CVE-2025-6543 was published on June 25, 2025 and was last updated on October 24, 2025. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CISA KEV·Added 2025-06-30 — agencies required to remediate by 2025-07-21

CVE-2025-6543

CRITICAL

Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy,…

Published

Jun 25, 2025

Updated

Oct 24, 2025

Affected

0 pkgs

Patched

None yet

Exploits

2 known

EPSS Exploitation Probability

via FIRST.org ↗

1.1%probability of exploitation in next 30 days

Lower Risk78th percentile0.00%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Description

Memory overflow vulnerability leading to unintended control flow and Denial of Service in NetScaler ADC and NetScaler Gateway when configured as Gateway (VPN virtual server, ICA Proxy, CVPN, RDP Proxy) OR AAA virtual server

Affected Products

2 products · 6 configurations

Application

netscaler application delivery controllercitrix

≥ 14.1 && < 14.1-47.46

range

Application

netscaler gatewaycitrix

≥ 14.1 && < 14.1-47.46

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

abrewer251/CVE-2025-6543_CitrixNetScaler_PoC

Multi-host, multi-port scanner and auditor for CVE-2025-6543-affected Ne

⭐ 5🍴 1Nov 2025

grupooruss/Citrix-cve-2025-6543

Script para determinar si Citrix es vulnerable al CVE-2025-6543

⭐ 4🍴 0Aug 2025

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2025-6543 in your stack?

O3 detects CVE-2025-6543 across dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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